This change bakes binary search table which maps PC ranges
to corresponding stack maps and Code objects (if still present
in the snapshot) into RO data section of the snapshot - instead
of constructing it at load time.
This allows to considerably reduce amount of work done when
loading Code cluster for programs which have majority of their
Code objects discarded (i.e. in DWARF stack traces mode): as
we no longer write / read any information for discarded Code
objects.
This CL also changes program visitor to deduplicate Code objects
if their instructions are deduplicated in AOT mode. Only a single
Code object can be choose as a representative for the given
PC range so it does not make sense to write multiple Code objects
into the snapshot which refer to the same Instructions.
The overall improvement is hard to quantify but ReadProgramSnapshot
shows the following improvement when starting a large
Flutter application on a slow Android device:
before 223.55±59.94 (192.02 .. 391.74) ms
after 178.06±47.03 (151.31 .. 291.34) ms
This CL packs CompressedStackMaps next to the binary search table
itself allowing us to address them via offsets instead of
pointers.
Snapshot sizes are actually affected positively by this change. On
the same large Flutter application I see
DWARF stack traces on: -1.34% total SO size
DWARF stack traces off: -1.63% total SO size
Issue https://github.com/dart-lang/sdk/issues/46116
TEST=ci
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Change-Id: Ic997045a33daa81ec68df462a0792915885df66b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/220766
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
While deserializing AOT snapshot, Code objects which do not contain
valuable information besides entry point and stack maps are discarded
and not allocated on the heap (they are replaced with
StubCode::UnknownDartCode()).
PC -> Code/CompressedStackMaps lookup is implemented using a separate
table (InstructionsTable).
Flutter gallery in release-sizeopt mode:
Heap size of snapshot objects: arm -26.89%, arm64 -27.68%
Large Flutter application in release mode with --dwarf-stack-traces:
Heap size of snapshot objects: -24.3%.
Discarded Code objects: 72.5% of all Code objects.
Issue: https://github.com/dart-lang/sdk/issues/44852.
TEST=existing tests; "--dwarf_stack_traces --no-retain_function_objects
--no-retain_code_objects" mode is enabled for a few tests.
Change-Id: I5fe3e283630c8e8f4442319d5dcae38d174dd0d8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/189560
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
This is a reland of b6dc4dad4d
TEST=ci
Original change's description:
> [vm/aot] Avoid using most Code objects in stack traces with --dwarf-stack-traces
>
> The following changes are done in preparation for the removal of Code
> objects in AOT with --dwarf-stack-traces:
>
> * Stack trace objects are extended to hold uword PCs (which may not
> fit into Smi range).
>
> * Scanning stack frames in GC (StackFrame::VisitObjectPointers)
> now avoids using Code objects.
> In order to find CompressedStackMaps it now calls
> ReversePc::FindCompressedStackMaps.
>
> * Singleton Code object (StubCode::UnknownDartCode()) is prepared as
> a replacement for Code objects in stack traces. It has
> PayloadStart() == 0 and Size() == kUwordMax so it includes
> arbitrary PCs.
>
> * In --dwarf-stack-traces mode, most Code objects obtained from stack
> frames are replaced with StubCode::UnknownDartCode().
> This simulates future behavior of ReversePc::Lookup when Code objects
> will be removed.
>
> Issue: https://github.com/dart-lang/sdk/issues/44852
> Change-Id: I7cec7b8b9396c9cfeca3c256a412ba4e82a7e0c4
> TEST=ci
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/182720
> Commit-Queue: Alexander Markov <alexmarkov@google.com>
> Reviewed-by: Tess Strickland <sstrickl@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
Change-Id: Ia2fc4672a085cd963b7fc103369851df3603590c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/186202
Commit-Queue: Vyacheslav Egorov <vegorov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
This reverts commit b6dc4dad4d.
Reason for revert: broke package:vm_snapshot_analysis in Flutter
(https://github.com/flutter/flutter/issues/76313).
Original change's description:
> [vm/aot] Avoid using most Code objects in stack traces with --dwarf-stack-traces
>
> The following changes are done in preparation for the removal of Code
> objects in AOT with --dwarf-stack-traces:
>
> * Stack trace objects are extended to hold uword PCs (which may not
> fit into Smi range).
>
> * Scanning stack frames in GC (StackFrame::VisitObjectPointers)
> now avoids using Code objects.
> In order to find CompressedStackMaps it now calls
> ReversePc::FindCompressedStackMaps.
>
> * Singleton Code object (StubCode::UnknownDartCode()) is prepared as
> a replacement for Code objects in stack traces. It has
> PayloadStart() == 0 and Size() == kUwordMax so it includes
> arbitrary PCs.
>
> * In --dwarf-stack-traces mode, most Code objects obtained from stack
> frames are replaced with StubCode::UnknownDartCode().
> This simulates future behavior of ReversePc::Lookup when Code objects
> will be removed.
>
> Issue: https://github.com/dart-lang/sdk/issues/44852
> Change-Id: I7cec7b8b9396c9cfeca3c256a412ba4e82a7e0c4
> TEST=ci
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/182720
> Commit-Queue: Alexander Markov <alexmarkov@google.com>
> Reviewed-by: Tess Strickland <sstrickl@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
Issue: https://github.com/dart-lang/sdk/issues/44852
Change-Id: I6f66171eecf1133363a7ce56193e782e43a20baf
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/185488
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
The following changes are done in preparation for the removal of Code
objects in AOT with --dwarf-stack-traces:
* Stack trace objects are extended to hold uword PCs (which may not
fit into Smi range).
* Scanning stack frames in GC (StackFrame::VisitObjectPointers)
now avoids using Code objects.
In order to find CompressedStackMaps it now calls
ReversePc::FindCompressedStackMaps.
* Singleton Code object (StubCode::UnknownDartCode()) is prepared as
a replacement for Code objects in stack traces. It has
PayloadStart() == 0 and Size() == kUwordMax so it includes
arbitrary PCs.
* In --dwarf-stack-traces mode, most Code objects obtained from stack
frames are replaced with StubCode::UnknownDartCode().
This simulates future behavior of ReversePc::Lookup when Code objects
will be removed.
Issue: https://github.com/dart-lang/sdk/issues/44852
Change-Id: I7cec7b8b9396c9cfeca3c256a412ba4e82a7e0c4
TEST=ci
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/182720
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
- Don't use PC-relative calls when calling between loading units.
- Sort the contents of the code cluster by loading unit, then by text offset.
- Handle binding PC-relatives calls and inserting trampolines per loading unit.
- Create one code order table per loading unit to implement PC -> Code lookup.
- Read code order tables directly, instead of copying into malloc'd memory.
--use_table_dispatch still not yet supported.
This slightly shrinks non-split binaries (~2% clustered part, 0.4% total snapshot) due to the new delta encoding when Code references Instructions.
Bug: https://github.com/dart-lang/sdk/issues/41974
Change-Id: I51052ebc7b4968b554897d1710135a6c41821302
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/157820
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
Now, when writing an AOT snapshot in bare instructions mode, only
the actual instructions in the RawInstructions payload are serialized
instead of the entire RawInstructions object.
Since there are no longer RawInstructions objects in these AOT
snapshots, we also change how Code objects are serialized. Instead
of just containing a reference to the RawInstructions object, we
serialize two pieces of information: where the instructions
payload for this Code object begins and whether there was a single
entry for the instructions payload. (To save space, the single
entry bit is serialized as the low order bit of the unchecked
offset, which was already being serialized).
While we also need the length of the instructions payload, we
approximate it for all but the last Code object by subtracting
the next Code object's payload start from this Code object's
payload start. For the last Code object, we assume it extends
to the end of the instructions image.
Changes on flutter gallery in release mode:
armv7: instructions size -2.70%, total size -1.73%
armv8: instructions size -6.04%, total size -3.63%
Fixes https://github.com/dart-lang/sdk/issues/38451.
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Change-Id: Ia0a5c4e5e47c956776dc62503da38ec55a143c04
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/134325
Commit-Queue: Teagan Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
This reverts commit 7475c637c3.
Reason for revert: Breakage on simarm_x64 (and thus arm_x64)
Original change's description:
> [vm/aot] Remove object wrapping of bare instructions for AOT snapshots.
>
> Now, when writing an AOT snapshot in bare instructions mode, only
> the actual instructions in the RawInstructions payload are serialized
> instead of the entire RawInstructions object.
>
> Since there are no longer RawInstructions objects in these AOT
> snapshots, we also change how Code objects are serialized. Instead
> of just containing a reference to the RawInstructions object, we
> serialize two pieces of information: where the instructions
> payload for this Code object begins and whether there was a single
> entry for the instructions payload. (To save space, the single
> entry bit is serialized as the low order bit of the unchecked
> offset, which was already being serialized).
>
> While we also need the length of the instructions payload, we
> approximate it for all but the last Code object by subtracting
> the next Code object's payload start from this Code object's
> payload start. For the last Code object, we assume it extends
> to the end of the instructions image.
>
> Changes on flutter gallery in release mode:
> armv7: instructions size -2.66%, total size -1.68%
> armv8: instructions size -5.81%, total size -3.49%
>
> Fixes https://github.com/dart-lang/sdk/issues/38451.
>
> Change-Id: Ia458e8d99bae18f5c3b6e849df2519027f06f574
> Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-release-x64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-linux-release-simarm_x64-try,vm-kernel-precomp-android-release-arm64-try,vm-kernel-precomp-android-release-arm_x64-try,vm-kernel-precomp-mac-release-simarm64-try,vm-kernel-precomp-win-release-x64-try
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/131067
> Commit-Queue: Teagan Strickland <sstrickl@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
TBR=kustermann@google.com,rmacnak@google.com,sstrickl@google.com
Change-Id: If2c8ca6b0993211b2509b275af7ff11a8fa2baa3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
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Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/134322
Reviewed-by: Teagan Strickland <sstrickl@google.com>
Commit-Queue: Teagan Strickland <sstrickl@google.com>
Now, when writing an AOT snapshot in bare instructions mode, only
the actual instructions in the RawInstructions payload are serialized
instead of the entire RawInstructions object.
Since there are no longer RawInstructions objects in these AOT
snapshots, we also change how Code objects are serialized. Instead
of just containing a reference to the RawInstructions object, we
serialize two pieces of information: where the instructions
payload for this Code object begins and whether there was a single
entry for the instructions payload. (To save space, the single
entry bit is serialized as the low order bit of the unchecked
offset, which was already being serialized).
While we also need the length of the instructions payload, we
approximate it for all but the last Code object by subtracting
the next Code object's payload start from this Code object's
payload start. For the last Code object, we assume it extends
to the end of the instructions image.
Changes on flutter gallery in release mode:
armv7: instructions size -2.66%, total size -1.68%
armv8: instructions size -5.81%, total size -3.49%
Fixes https://github.com/dart-lang/sdk/issues/38451.
Change-Id: Ia458e8d99bae18f5c3b6e849df2519027f06f574
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-release-x64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-linux-release-simarm_x64-try,vm-kernel-precomp-android-release-arm64-try,vm-kernel-precomp-android-release-arm_x64-try,vm-kernel-precomp-mac-release-simarm64-try,vm-kernel-precomp-win-release-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/131067
Commit-Queue: Teagan Strickland <sstrickl@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
This CL adds a [ReversePcLookupCache] which, based on a list of code
objects, builds up a binary searchable table for mapping PCs to Code
objects (where all the metadata is available, like stackmaps, ...).
This CL also adds stack walking support for "bare instruction" frames.
In a later part we will start emitting the sorted list of code objects
(via the new field in the object store) under a flag.
Issue https://github.com/dart-lang/sdk/issues/33274
Change-Id: I3c06c12bc0fb266dc1bd843a4a11b5208773151d
Reviewed-on: https://dart-review.googlesource.com/c/85746
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Vyacheslav Egorov